It is (at least after a certain young age). There's been a lot of research around this because the incentive is huge. Military has spent quite a bit of money on that too (IARPA). So far, science tells us that it is fixed. I mean, you can lower it with some brain injuries but you pretty much cannot increase it[1].
I know it ruins some American Dream ideas, people with IQ below 80 are pretty much not employable, but that's just how it is. Some people have much harder time achieving things that others do with ease and we don't know any way to help them. For some reason people see it in a very different light than e.g. somebody having some disease that he has to organize his life around it or e.g. being paralyzed.
the cognitive benefits of modafinil seem particularly marked in tests of vigilance and speed, in which sleepiness would be an important factor. Furthermore, the results indicate that high IQ may limit detection of modafinil's positive effects.
Unfortunately no, I don't have any concrete evidence on that point, just some amount of anecdata from people who are "nootropic" enthusiasts that I found convincing enough.
Give them the test one more time after modafinil wears off and they score even higher ;)
Some references are welcome. Pure guess, but we do know that most society is sleep deprived and that sleep deprivation affects cognitive performance. As far as I understand it, modafinil can alleviate that.
That may be what was happening --It makes me wonder, if we say that someones higher baseline intelligence is hidden behind some semi-permanent condition like chronic inflammation or poor sleep patterns, is that really their baseline? How many other factors may be "artificially" decreasing someones measurable general intelligence for most or all of their life?
I'm not sure about this, but i have no study, only anecdot.
I scored 123 at 8 or 9 on the weshler test, and 90 on the spatial visualization part. (that mean that around 60% of the european population was better than me at spatial visualization when i was a kid). However, i'm able to play blindchess and chart a course since i'm a teen, i was probably one of the best at understanding geometry/vectors in highschool and the only math course i wasn't bad at in college were topology and n-dimmension vectorized spaces. If i "blundered" the IQ test, i'm not aware of it (i know i wasn't very cooperative, but still). Maybe i misundertand what spatial vizualisation mean, but i don't think so.
Oh and also one part of the test was general knowledge, and i don't believe it can't be trained (like the puzzles/tangrams, symbol recognition or verbal expression tests).
If you're right, then it's reassuring for me since i feel like i'm more dumb on multiple subject than when i was a kid.
I don't believe in that science. The brain can learn how to approach problems more efficiently, how to break them down, how to think in the way these IQ tests are designed.
We put way too much confidence into science in general. It's our God we don't question.
Sometimes this is true of the scientists but not the general populous, they can tend to hold onto ideas that were once accepted science and turned out inaccurate.
I know it ruins some American Dream ideas, people with IQ below 80 are pretty much not employable, but that's just how it is. Some people have much harder time achieving things that others do with ease and we don't know any way to help them. For some reason people see it in a very different light than e.g. somebody having some disease that he has to organize his life around it or e.g. being paralyzed.
1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3950413/
edit: btw I love and highly recommend Brain That Changes Itself book, by Norman Doidge, but this is something different